The DVD-Video standard is one of the standards for encoding a moving image and recording the encoded moving image on a DVD (Digital Versatile Disc) and is widely adopted for commercial video cameras and video recorders (see, for example, Patent Document 1).
FIG. 1 is a diagram showing horizontal×vertical resolutions acceptable to MPEG (Moving Picture Experts Group) 2 video recorders that perform recording operations in compliance with the DVD-Video standard. In the NTSC (National Television System Committee) television system, four types of horizontal×vertical resolution such as 720×480, 704×480, 352×480, and 352×240 can be accepted. However, in a case where the aspect ratio of an encoded moving image is 16:9, the resolutions of 352×480 and 352×240 cannot be accepted. In the PAL television system, four types of horizontal×vertical resolution such as 720×576, 704×480, 352×576, and 352×288 can be accepted. However, in a case where the aspect ratio of an encoded moving image is 16:9, the resolutions of 352×576 and 352×288 cannot be accepted.
In other words, in the DVD-Video standard, in a case where the aspect ratio of a moving image recorded by an MPEG2 video recorder is 16:9, the value of a horizontal resolution selectable for an encoding operation performed on the moving image is limited to 704 or 720.
Accordingly, in known video cameras, video recorders, etc. strictly compliant with the DVD-Video standard, a combination of the aspect ratio of a recorded moving image and a recording mode concerned with a value of a horizontal resolution, etc. is controlled, for example, as shown in FIG. 2.
Referring to the example shown in FIG. 2, three types of recording mode are provided. An HQ mode has a resolution of 720×480, where the highest-quality encoding is performed. An SQ mode has a resolution of 720×480, where the second-highest-quality encoding is performed. An LP mode has a resolution of 352×480, where encoding enabling longer-time recording of a moving image on a recording medium with the same capacity as recording media used in other modes is performed. In this case, however, the quality of the recorded moving image becomes lower than that of the recorded moving image acquired when the HQ or SQ mode is used.
For example, when a user sets an aspect ratio of a moving image to be recorded to 4:3, or when an aspect ratio of a moving image having been input so as to be recorded is 4:3, any of the HQ, SQ, and LP modes can be selected.
However, when the user sets an aspect ratio of a moving image to be recorded to 16:9, or when an aspect ratio of a moving image having been input so as to be recorded is 16:9, the LP mode having a horizontal resolution of 352 cannot be selected.
In contrast, when the user selected the LP mode that has a horizontal resolution of 352, the user cannot set an aspect ratio of a moving image to be recorded to 16:9.
In a case where a bit rate is set to a low value so that a minimum recording length of a recording medium such as a DVD can be extended, the amount of information per pixel can be more increased by encoding a moving image that has an aspect ratio of 16:9 at a horizontal resolution of 352 rather than 704 or 720. Consequently, improvement in quality of the encoded moving image can be expected.
Therefore, there have been video cameras or the like that encode a moving image that has an aspect ratio of 16:9 at a horizontal resolution of 352 and record the encoded moving image in spite of adopting the DVD-Video standard.
In these video cameras, a moving image is recorded using a format not compliant with the DVD-Video standard, and information showing that the moving image has the aspect ratio of 4:3 is recorded at a predetermined position on the format.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2004-201170